Anyone know if they are going to build a barclays app like natwest have done?

Not unless they build their own app. The Natwest, RBS & Ulster apps are all developed by Monilink. We would only see these apps for the following banks who support Monilink: NatWest, RBS, HSBC, First Direct, Lloyds TSB, Alliance & Leicester and Ulster Bank. Any others would be developed independently, unless they join. This site indicates they are in talks with all the major banks though, so it may happen at some stage: